The present invention relates to a data recording apparatus such as an optical disk apparatus for recording/reproducing image data.
An optical disk apparatus optically records data on or reproduces it from an optical disk by scanning the rotating optical disk with a laser beam. The optical disk has received much attention as a hitherto unknown large-capacity memory. For example, the optical disk can be applied to a large-capacity image file apparatus.
Among the optical disk apparatuses of this type, an apparatus is being developed such that recording tracks are formed by grooves called pregrooves (or prepit array) in a spiral (or concentrical) manner, and that a recording beam is radiated on the optical disk so as to form a data pit in the pregroove while a reproducing beam traces the pregroove, thereby recording image data. In this case, the single laser beam is switched between the reproducing beam and the recording beam having higher energy than the reproduction beam.
In the optical disk apparatus of the type described above, an optical head driven by a linear motor in the radial direction of the optical disk is used to record the data on or reproduce it from the optical disk. The optical head is positioned by a position sensor which comprises an optical mask and an optical non-contact linear scale of an overlap grating.
However, in the optical disk apparatus of this type, precise positioning cannot be performed due to a mounting error of the optical scale, a change in temperature and humidity, and a manufacturing error. For these reasons, after optical head access is made to a track and the track number of this track is detected, the optical head is then accessed to a desired track. Therefore, the access time is increased, and control is complicated.